Orifice plate meters are a popular for being relatively simple, reliable and inexpensive. Their principles of operation are easily understood. However, traditionally there has been no orifice meter self diagnostic capabilities. In 2008 & 2009 a generic Differential Pressure (DP) meter self diagnostic methodology [1,2] was proposed. In this paper these diagnostic principles are applied to orifice meters and proven with experimental test results. The diagnostic results are presented in a simple graphical form designed for easy use in the field by the meter operator.